Labunchkin
A loudmouth who brags about everything and everyone else's failures, but they're just a big mess who can't even handle their own life.
My uncle is a labunchkin. He said he can run a marathon. He fell asleep halfway through.
My coworker is a labunchkin. She said she can solve any problem. She couldn't fix her coffee maker.
My mom is a labunchkin. She said she can cook a 5-star meal. She burned the toast.